Fluorosurfactants having improved biodegradability

ABSTRACT

To address the problem of insufficient biodegradability of perfluorinated surfactants, the present invention provides biodegradable fluorosurfactants derived from olefins having —CHR, —CHRf, —CHF, and/or —CH 2  groups, where R is an alkyl group and Rf is a perfluoro or fluroroalkyl group. Preferably, the —CHR, —CHRf, —CHF, and/or —CH 2  groups are contained within partially fluorinated alkenes.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of PCT Application No.PCT/US14/051807, filed Aug. 20, 2014, which application claims priorityfrom U.S. Provisional Application Ser. No. 61/873,675 filed Sep. 4,2013, the disclosure of each which is hereby incorporated herein byreference.

FIELD OF THE INVENTION

The present invention relates to the production of fluorosurfactantshaving improved biodegradability. More specifically, the presentinvention relates to biodegradable fluorosurfactants produced fromolefins comprising —CHR, —CHRf, —CHF, and/or —CH₂ groups, wherein R isan alkyl group and Rf is a perfluoro or fluroroalkyl group.

BACKGROUND OF THE INVENTION

Fluorosurfactants have many unique properties, and are useful as soiland water repellents, airplane hydraulic fluids, additives infirefighting foams, paints, coatings, clothing, carpets, leather, waxes,polishes, and the like. Fluorosurfactants like perfluorooctanoic acid(PFOA) are also used as surfactants in aqueous media for thepolymerization of hydrophobic monomers, especially fluorinated monomerssuch as tetrafluoroethylene. See Erik Kissa, Fluorinated Surfactants andRepellents, Surfactant Science Series, Vol. 97, 2nd edition (2001)(“Kissa”). The most commonly used fluorosurfactants areperfluorooctanoic acid (PFOA, C₇F₁₅CO₂H) and perfluorooctane sulfonate(PFOS, C₈F₁₇SO₃X, X═K, Na, H).

Typically, fluorosurfactants are compounds having a hydrophobic(generally a perfluoroalkyl chain) and a hydrophilic moiety (generallycarboxylate/sulfate/quaternary ammonium moiety, or the like). When thehydrophobic chain is a perfluoroalkyl group, such as the C₇F₁₅ or C₈F₁₇,groups of PFOA and PFOS, respectively, such compounds are highlyresistant to biodegradation. However, the fluorosurfactants having suchperfluoroalkyl hydrophobic chains are persistent, toxic, bioaccumulable,and accordingly are found in blood of many animals and humans all overthe world. See, e.g., M. Houde et al., Environ. Sci. Tech. 40, (2006),3463-3473; Boutevin, et al., J. Fluorine Chem. 134, (2012), 77-84.Accordingly, it is even possible that the United States EnvironmentalProtection Agency (EPA) may eliminate the use of PFOA and PFOS in thenear future owing to environmental concerns. There is thus a significantand urgent need in developing alternate fluorosurfactants that arebiodegradable and environmentally friendly (see H. J. Lehmler,Chemosphere, 58, (2005), 1471-1496; G. Kostov et al., J. Fluorine Chem.130, (2009), 1192-1199).

SUMMARY OF THE INVENTION

To address the problem of insufficient biodegradability, the presentinvention provides biodegradable fluorosurfactants derived fromcommercially available raw materials, i.e., from olefins comprising—CHR, —CHRf, —CHF, and/or —CH₂ groups.

Thus, one embodiment of the invention is a fluorosurfactant having thegeneral formula Rf—X—Y, wherein Rf is a perfluorinated alkyl group, X isa fluoroolefin, Y is a neutral group, such as OH, or a hydrophilicgroup, and wherein the surfactant is biodegradable.

In certain embodiments, the fluorosurfactant of formula Rf—X—Y includesX which is derived from a partially fluorinated alkene.

In certain embodiments, the fluorosurfactant of formula Rf—X—Y includesa partially fluorinated alkene which is selected from the groupconsisting of CF₂═CFCl, CH₂═CHF, CHF═CHF, CH₂═CF₂, CF₃CH═CHCF₃,CF₃CF═CFCF₃, CF₃C═H, and (CF₃)₂CF—CF═CFCF₃ (HFP dimer).

In certain embodiments, the fluorosurfactant of formula Rf—X—Y includesX which is derived from a partially fluorinated propene.

In certain embodiments, the fluorosurfactant of formula Rf—X—Y includesa partially fluorinated propene which is selected from the groupconsisting of CF₃CF═CH₂ (HFO-1234yf), CF₃CH═CHF (HFO 1234ze), CF₃CF═CHF(HFO-1225yf), CF₃CH═CHCl (HCFO-1233zd), CF₃CH═CH₂, CF₃CH═CF₂, CF₃CF═CF₂,CF₃CH≡CH, (CF(CF₃)(CF₂H)H, and hexfluoropropene trimer.

In certain embodiments, the fluorosurfactant is an anionic surfactant.

In certain embodiments, the anionic surfactant is selected from thegroup consisting of carboxylates, sulfonates, sulfates, phosphates, andmixtures thereof.

In certain embodiments, the fluorosurfactant is a cationic surfactant.

In certain embodiments, the cationic surfactant is selected from thegroup consisting of amino, amido, ammonio, sulfonamido salts, andmixtures thereof.

In certain embodiments, the fluorosurfactant is an amphotericsurfactant.

In certain embodiments, the amphoteric surfactant is selected from thegroup consisting of carboxybetaine, sulfobetaine, sulfatobetaine, andmixtures thereof.

In certain embodiments, the fluorosurfactant is a nonionic surfactant.

In certain embodiments, the nonionic surfactant is selected from thegroup consisting of oxyethylated phenols, oxyethylated alcohols,polyhydric alcohols, and mixtures thereof.

DETAILED DESCRIPTION OF THE INVENTION

As described above, in order to address the problem of insufficientbiodegradability of perfluorinated surfactants, the present inventionprovides biodegradable fluorosurfactants derived from olefins having—CHR, —CHRf, —CHF, and/or —CH₂ groups, where R is an alkyl group and Rfis a perfluoro or fluroroalkyl group. Preferably, the —CHR, —CHRf, —CHF,and/or —CH₂ groups are contained within partially fluorinated alkenes.

In accordance with the present invention, each of the four major classesof Surfactants—anionic, cationic, amphoteric and nonionic—may beprepared. Example anionic surfactants include carboxylates, sulfonates,sulfates, and phosphates; example cationic surfactants include amino,amido, ammonio, and sulfonamido salts; example amphoteric surfactantsinclude carboxybetaine, sulfobetaine, and sulfatobetaine; and examplenonionic surfactants include oxyethylated phenols, as well asoxyethylated and polyhydric alcohols. General examples for each of thesesurfactants are provided below:

RfCO₂ ⁻Na⁺/RF SO₃ ⁻Na⁺,   1)

RfC(O)NH(CH₂)₃ N⁺CH₃I⁻,   2)

RfXYN⁺(CH₃)₂(CH₂)_(n)CO₂ ⁻/SO₃ ⁻/OSO₃ ⁻, and   3)

RfCH₂O(CH₂CH₂O)_(n)H, respectively.   4)

wherein n is an integer and Rf is F-alkyl group comprising at least onehydrogen, and having a straight or branched chain.

Preferably, the above fluorosurfactants are derived from a number offluoroolefins (X) that are available at Honeywell or from commercialvendors. Examples include CF₃CF═CH₂ (HFO-1234yf), CF₃CH═CHF(HFO-1234ze), CF₃CF═CHF (HFO-1225yf), CF₃CH═CHCl (HCFO 1233zd),CF₃CH═CH₂, CF₃CH═CF₂, CF₂═CFCl, CH₂═CHF, CHF═CHF, CH₂═CF₂, CF₃CH═CHCF₃,CF₃CF═CF₂, CF₃CF═CFCF₃, CF₃C═H, (CF₃)₂CF—CF═CFCF₃ (HFP dimer), CF₃CH≡CH,(CF(CF₃)(CF₂H)H, and hexfluoropropene trimer. Such surfactants can beprepared using procedures similar to those detailed on pages 1-21 ofKissa, which is incorporated herein by reference.

In accordance with one embodiment of the present invention, alcoholsderived from the above olefins for example, CF₃CFHCF₂CH₂OH and(CF₃)₂CF—CFH—CF(CF₃)CH₂OH, can also be employed. As shown in Equation 1,short chain perfluoroalkyl iodides Rf-I (Rf═CF₃, C₂F₅, C₃F₇, C₄F₉) canbe added to these olefins in the presence of a radical initiator such asditertiary butyl peroxide, AIBN, benzoyl peroxide or UV light to affordthe adduct:

Rf—I+X→Rf—[X]_(n)—I   (Eq. 1)

wherein Rf=CF₃, C₂F₅, C₃F₇ or C₄F₉ and X=CF₃CF═CH₂ (HFO-1234yf),CF₃CH═CHF (HFO-1234ze), CF₃CF═CHF (HFO-1225yf), CF₃CH═CHCl (HCFO1233zd), CF₃CH═CH₂, CF₃CH═CF₂, CF₂═CFCl, CH₂═CHF, CHF═CHF, CH₂═CF₂,(CF₃)₂CF—CF═CF(CF₃), CF₃CF═CF₂, CF₃CH═CH (CF(CF₃)(CF₂H)H, orhexfluoropropene trimer. X includes all isomers.

In accordance with a second embodiment of the present invention, auseful class of precursors for surfactants is alcohols. Alcoholderivatives of X compounds can be made by the addition of methanol toolefins (see Equation 1a) or from compounds of formula

Rf[X]_(n)—[(CH₂—CH₂)]_(m)I:

X+CH₃OH→H—X—CH₂OH   (Eq. 1a)

wherein X is as defined in Equation 1.

In accordance with a third embodiment of the present invention, ethylenecan be added to compounds of formula Rf—[X]_(n)—I to afford ethylenatedproduct as given below in Equation 2:

Rf—[X]_(n)—I+CH₂═CH₂→Rf—[X]_(n)—[(CH₂—CH₂)]_(m)I   (Eq. 2)

wherein m=1 or 2. Various conditions can be employed to get the desirednumber of m.

Compounds of formula Rf—[X]_(n)—[(CH₂—CH₂)]_(m)I can be converted tovarious classes of surfactants by functionalizing with varioushydrophilic groups (Y) including carboxylates, sulfonates, phosphates,ammonium salts, various betaines, ethoxylated alcohol and the like asshown in Equation 2 a, and as described on pages 29-79 of Kissa, whichis incorporated herein by reference:

Rf—[X]_(n)—[(CH₂-CH₂)]_(m)I→Rf—[X]_(n)—CH₂—Y   (Eq. 2a)

wherein Y=a carboxylate, sulfate, sulfonate, phosphate, quaternaryammonium, carboxybetaine, sulfobetaines, sulfatobetaine,phosphatobetaine, or alcohol group.

Representative examples include:

Rf—[X]_(n)—CH₂—CO₂H; Rf—[X]_(n)—CH₂—CO₂Na;

Rf—[X]_(n)—CH₂—SO₃H; Rf—[X]_(n)—CH₂—SO₃Na; Rf—[X]_(n)—CH₂—OP(O)(OH)₂;

Rf—[X]_(n)—CH₂—CH₂—N⁺(CH₃)₃ I⁻; Rf[X]_(n)—CH₂CH₂SO₂NH(CH₂)₃N⁺(CH₃)₃ I⁻;

Rf—[X]_(n)—CH₂CH₂N^(+ (CH) ₃)₂CH₂CO₂ ⁻; Rf—[X]_(n)—CH₂CH₂SCH₂CH₂N(CH₃)₂⁺CH₂CO₂ ⁻;

Rf—[X]_(n)—CH₂—O(CH₂CH₂O)_(n)H; and,Rf—[X]_(n)—CONH(CH₂)₃N(CH₂CH₂O)_(n)H,

wherein n in the above formulae denotes an integer.

In accordance with a fourth embodiment of the present invention,preparation of carboxylic acids can be achieved by converting theF-alkyl iodides to the respective alcohol, which is then oxidized tocarboxylic acid (see Equation 3) with a suitable reagent such HNO₃, andalternatively, the iodides can also be converted to acid with a reagentcombination of K₂Cr₂O₇/H₂SO₄ (see Equation 4):

Rf—[X]—CH₂CH₂I→Rf—[X]—CH₂CH₂OH→Rf—[X]—CH₂CO₂H   (Eq. 3)

Rf—[X]—CH₂CH₂I (K₂Cr₂O₇/H₂SO₄)→Rf—[X]—CH₂CO₂H   (Eq. 4)

Respective salts can be obtained by treating the acids with sodium orpotassium hydroxide, and F-alkyl iodides can be converted to sulfonicacids by many well established methods in the art.

In accordance with a fifth embodiment of the present invention, as shownin Equations 5 and 6, cationic surfactants are prepared by differentmethods known in the art, e.g., by treating sulfonyl chloride halidewith an amine and then quaternizing with an alkyl halide.

Rf—[X]—CH₂CH₂SO₂Cl+(CH₃)₂N(CH₂)₃NH₂→

Rf—[X]—CH₂CH₂SO₂NH(CH₂)₃N(CH₃)₂   (Eq. 5)

Rf—[X]—CH₂CH₂SO₂NH(CH₂)₃N(CH₃)₂+CH₃I→

Rf—[X]—CH₂CH₂SO₂NH(CH₂)₃N^(+ (CH) ₃)₃I⁻  (Eq. 6)

In accordance with a sixth embodiment of the present invention,amphoteric surfactants such as betaines are prepared as shown inEquations 7 and 8. For example, carboxy betaines may be prepared bytreating F-alkyl tertiaryamine with chloro acetic acid or its sodiumsalt. Carboxy-betaines with sulfide linkage may be prepared by treatingF-alkyl iodide with (2-mercaptoethyl)dimethylammonium chloride andsubsequent quaternization with chloroacetic acid.

Rf—[X]—CH₂CH₂I+HSCH₂CH₂N(CH₃)₂.HCl+NaOH→

Rf—[X]—(CH₂)₂SCH₂CH₂N(CH₃)₂   (Eq. 7)

Rf—[X]—(CH₂)₂SCH₂CH₂N(CH₃)₂+ClCH₂CO₂H→

Rf—[X]—(CH₂)₂SCH₂CH₂N⁺ (CH₃)₂CH₂CO₂ ⁻  (Eq. 8)

As shown in Equation 9, nonionic F-alkyl surfactants can be prepared bystraight forward oxyethylenation in the presence of catalyst, forexample, boron trifluoride (BF₃ cat).

Rf—[X]—CH₂CH₂OH+Ethylene oxide+(BF₃ cat)→

Rf—[X]—CH₂CH₂O(CH₂CH₂O)_(n)H   (Eq. 9)

EXAMPLES Example 1 Addition of C₂F₅I to CF₃CH═CHF

Into a clean, dry and evacuated 650 ml autoclave (Parr® reactor) wasadded ditertiarybutyl peroxide (10.5 g) and C₂F₅I (75 g). The autoclavewas then cooled with dry ice and condensed 65 g CF₃CH═CHF. The reactorwas brought to room temperature and heated to and maintained at 145° to150° C. for 6 hrs; the reactor was then brought to room temperature,vented of volatile materials, and the contents in the autoclave werepoured into cold water. The separated organic phase was washed with 5%aq. sodium bisulphite (20 mL), water(20 mL) and brine (20 mL), dried(MgSO₄), and distilled to afford CF₃CF₂[CHF—CH(CF₃)]_(n)—I (n=1).

Example 2

The reaction was conducted in the same manner as in Example 1, exceptthat CF₃CF═CHF was used instead of CF₃CH═CFH to affordCF₃CF₂[CHF—CF(CF₃)]_(n)—I (n=1).

Example 3

The reaction of C₂F₅I with CF₃CF═CH₂, CF₃H═CH₂, CF₂═CFCl, CF₃CF═CF₂,(CF₃)₂CF—CF═CF(CF₃), CF₃CH═CH(CH(CF₃)(CF₂H)) were carried out as inexample 1, and the following compounds were obtained:

CF₃CF₂[CF₃CF—CH₂]_(n)—I, CF₃CF₂[CF₃CH—CH₂]_(n)—I,CF₃CF₂[CF₂—CFCl]_(n)—I,

CF₃CF₂[CF₂—CF(CF₃)]_(n)—I, CF₃CF₂[(CF₃)CF—C(C₂F₅)—CF(CF₃)₂](isomers),and

CF₃CF₂[(CF₃)CH—CH—(CF(CF₃)(CF₂H))]_(n)—I (all n=1).

Example 4 Insertion of Ethylene into C—I Bond inCF₃CF₂[CHF—CH(CF₃)]_(n)—I (n=1)

A 400 mL autoclave was charged with CF₃CF₂[CHF—CH(CF₃)]_(n)—I (n=1) (72g, 0.2 mol), ethylene (6.25 g, 0.13 mol) and D (+)-limonene (0.4 g) andthe reactor was heated at 240° C. for 12 hours. The product formed wasthen transferred and distilled under reduced pressure to affordCF₃CF₂[CHF—CH(CF₃)]_(n)—(CH₂—CH₂)_(m)—I (n=m=1) as the major product(60%).

Example 5

In a similar manner, ethylenated compounds were prepared forCF₃CF₂[CF₃CF—CH₂]_(n)—I, CF₃CF₂[CF₃CH—CH₂]_(n)—I,CF₃CF₂[CF₂—CFCl]_(n)—I, CF₃CF₂[CF₂—CF(CF₃)]_(n)—I,CF₃CF₂[(CF₃)CF—C(C₂F₅)—CF(CF₃)₂]_(n)—I (isomers),CF₃CF₂[(CF₃)CH—CH—(CF(CF₃)—(CF₂H))]_(n)—I by following the procedure ofExample 4.

Example 6 Conversion of CF₃CF₂[CHF—CH(CF₃)]_(n)—(CH₂—CH₂)_(m)—I (n=m=1)to CF₃CF₂[CHF—CH(CF₃)]_(n)—(CH₂—CH₂)_(m)—SO₃Na.

A 500 mL flask equipped with a stirrer, condenser, a mixture ofCF₃CF₂[CHF—CH(CF₃)]_(n)—(CH₂—CH₂)_(m)—I (n=m=1) (0.2 mol), ethanol (100mL), water (100 mL), sodium sulfite (0.4 mol) and copper powder (4.8 g)was refluxed under nitrogen for a week. After this, 250 mL water wasadded, mixed well and filtered. The filtrate was cooled andcrystallized/precipitated using sodium salt, andCF₃CF₂[CHF—CH(CF₃)]_(n)—(CH₂—CH₂)_(m)—SO₃Na was separated by filtrationand dried (0.15 mol, 75%).

Example 7 Conversion of CF₃CF₂[CHF—(CF₃)CH]_(n)—I toCF₃CF₂[CHF—(CF₃)CH]_(n)—CH₂CO₂H/Na (n=1)

Conversion of CF₃CF₂[CHF—(CF₃)CH]_(n)—I toCF₃CF₂[CHF—(CF₃)CH]_(n)—CH₂CO₂H was effected as described in J. FluorineChem. 66, (1994), 249-252, incorporated herein by reference. Thus,CF₃CF₂[CHF—(CF₃)CH]_(n)—I was reacted with vinyl acetate toCF₃CF₂[CHF—(CF₃)CH]_(n)—CH₂CHIOCOCH₃, which was then hydrolyzed toaldehyde, CF₃CF₂[CHF—(CF₃)CH]_(n)—CH₂CHO, and finally oxidized to thedesired acid, CF₃CF₂[CHF—(CF₃)CH]_(n)—CH₂CO₂H. The acid was converted toits sodium salt by treating with equimolar amount of NaOH in water. In asimilar fashion, by employing the above procedure other iodides wereconverted to the respective acids/salts.

Example 8 Conversion of CF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)I (n=m=1) tobetaine derivativeCF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)N⁺(CH₃)₂CH₂CO₂HCl⁻

Part A: A solution of dimethylamine (0.025 mol) (33% in ethanol) andCF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)I (0.02 mol) was added to sodiumcarbonate (0.2 mol) in ethanol and water (60 mL+15 mL) solution andrefluxed for 24 hours. After this the reaction mixture was filtered, thefiltrate was washed with water (10 ml), extracted in ether (50 mL), anddried (Na₂SO₄) to afford the crude amine derivative which was distilledto afford CF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)N(CH₃)₂.

Part B: Subsequently, a stirred mixture ofCF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)N(CH₃)₂ (0.01 mol) and monochloroacetic acid (0.01 mol) was slowly heated (120° to 130° C.) for an hourin an oil bath to afford the productCF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)N⁺(CH₃)₂CH₂CO₂HCl⁻.

Example 9 Preparation ofCF₃CF₂[CHF—(CF₃)CH]_(n)—CH₂CH₂]_(m)SCH₂CH₂N⁺(CH₃)₂CH₂CO₂HCl⁻ (n=m=1)

Part A: To a stirred solution of NaOH (4.0 g, 0.1 mol) in absoluteethanol (50 mL) was added 0.05 mol of2-dimethylaminoethylthiohydrochloride, and the mixture was heated to 50°C. for 15 minutes. This solution was then added to a solution ofCF₃CF₂[CHF—(CF₃)CH]_(n)I (0.05 mol) in 100 mL tertiaryamyl alcohol andthe mixture was refluxed for 6 hours. After cooling to room temperature,the reaction mixture was filtered, concentrated on a rotavap, and theresidue extracted with ether (2×150 mL). The combined ether extractswere washed with 150 ml 5% aqueous NaOH, 100 mL water, dried (MgSO₄),and concentrated under reduced pressure to give a liquid residue—thecrude CF₃CF₂[CHF—(CF₃)CH]_(n)SCH₂CH₂N(CH₃)₂—which could be purified viadistillation.

Part B: The reaction was conducted exactly the same manner as describedin Example 8, part B, except that CF₃CF₂[CHF—(CF₃)CH]_(n)SCH₂CH₂N(CH₃)₂was used in place of CF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)N(CH₃)₂ toafford CF₃CF₂[CHF—(CF₃)CH]_(n)—[CH₂CH₂]_(m)SCH₂CH₂N⁺ (CH₃)₂CH₂CO₂HCl⁻.

Example 10 Conversion of (CF₃)₂CF—CFH—(CF₃)CF—CH₂OH to(CF₃)₂CF—CFH—(CF₃)CF—CH₂O—CH₂CH₂OH

Part A: Ethylene oxide (12.1 mmol) was allowed to react in diethyl etherwith 32 mmol (CF₃)₂CF-CFH-(CF₃)CF-CH₂OH in ether with BF₃ etheratecomplex (3.0 g) as the catalyst for 10 min at room temperature. Thereaction mixture was concentrated, extracted in ether, washed with 2%NaOH, washed with water, and dried to afford(CF₃)₂CF—CFH—(CF₃)CF—CH₂O—CH₂CH₂OH.

Part B: Ethylene oxide (12.1 mmol) was allowed to react in diethyl etherwith dehydrated alumina (10 g) and 32 mmol (CF₃)₂CF—CFH—(CF₃)CF—CH₂OHfor 10 min at room temperature. Filtration and work up afforded(CF₃)₂CF—CFH—(CF₃)CF—CH₂O—CH₂CH₂OH.

From the foregoing, it will be appreciated that although specificexamples have been described herein for purposes of illustration,various modifications may be made without deviating from the spirit orscope of this disclosure. It is therefore intended that the foregoingdetailed description be regarded as illustrative rather than limiting,and that it be understood that it is the following claims, including allequivalents, that are intended to particularly point out and distinctlyclaim the claimed subject matter.

What is claimed is:
 1. A fluorosurfactant having the general formulaRf—X—Y, wherein Rf is a perfluorinated alkyl group, X is a fluoroolefin,Y is a neutral group or a hydrophilic group, and wherein the surfactantis biodegradable.
 2. The fluorosurfactant of claim 1, wherein X isderived from a partially fluorinated alkene.
 3. The fluorosurfactant ofclaim 3, wherein the partially fluorinated alkene is selected from thegroup consisting of CF₂═CFCl, CH₂═CHF, CHF═CHF, CH₂═CF₂, CF₃CH═CHCF₃,CF₃CF═CFCF₃, CF₃C═H, and (CF₃)₂CF—CF═CFCF₃ (HFP dimer).
 4. Thefluorosurfactant of claim 2, wherein X is derived from a partiallyfluorinated propene.
 5. The fluorosurfactant of claim 3, wherein thepartially fluorinated propene is selected from the group consisting ofCF₃CF═CH₂ (HFO-1234yf), CF₃CH═CHF (HFO-1234ze), CF₃CF═CHF (HFO-1225yf),CF₃CH═CHCl (HCFO 1233zd), CF₃CH═CH₂, CF₃CH═CF₂, CF₃CF═CF₂, CF₃CH≡CH,(CF(CF₃)(CF₂H)H, and hexafluoropropene trimer.
 6. The fluorosurfactantof claim 1, which is an anionic surfactant.
 7. The fluorosurfactant ofclaim 6, wherein the anionic surfactant is selected from the groupconsisting of carboxylates, sulfonates, sulfates, phosphates, andmixtures thereof.
 8. The fluorosurfactant of claim 1, which is acationic surfactant.
 9. The fluorosurfactant of claim 8, wherein thecationic surfactant is selected from the group consisting of amino,amido, ammonio, sulfonamido salts, and mixtures thereof.
 10. Thefluorosurfactant of claim 1, which is an amphoteric surfactant.
 11. Thefluorosurfactant of claim 10, wherein the amphoteric surfactant isselected from the group consisting of carboxybetaine, sulfobetaine,sulfatobetaine, and mixtures thereof.
 12. The fluorosurfactant of claim1, which is a nonionic surfactant.
 13. The fluorosurfactant of claim 12,wherein the nonionic surfactant is selected from the group consisting ofoxyethylated phenols, oxyethylated alcohols, polyhydric alcohols, andmixtures thereof.